1. Field of the Invention
The present invention relates to a non-destructive inspection apparatus or method for inspecting drugs and food-products. More particularly, the present invention relates to a radiation inspection apparatus and a radiation inspection method suitable for inspecting an occurrence of a crack or a nick of a packaged object, whose inside cannot be observed with visual light owing to packaging materials.
2. Description of the Related Art
Hitherto, an inspection apparatus using visual or infrared light has been known as an apparatus for inspecting an occurrence of a crack and a nick of a packaged food-product. This inspection apparatus using visual light or infrared light usually irradiates an object to be inspected, which is packaged, with visual or infrared light and then receives light reflected or transmitted by the object by using a CCD camera. Thus, the inspection apparatus obtains image information concerning the inside of a package and determines whether or not abnormality, such as a crack and a nick, of the object included in the package occurs according to the shape thereof.
Meanwhile, in recent years, many kinds of aluminum foil and boxes, which are disabled to transmit light, have been employed as the manners of packaging food-products and drugs. Such inspection apparatuses using light are no use to inspect an occurrence of a crack or nick of the object packaged in such a manner.
Moreover, the inspection apparatus using light has a problem that, even if a packaging material constituted by a light-transmissive material is used, a result of inspection is significantly affected by the coloring of the surface of the packaging material.
It is sufficient for seeing the inner situation of the package wrapped by the packaging material made of a non-transmissive material therethrough to use an inspection apparatus using radiation, such as X-rays. In a conventional radiation inspection apparatus, radiation transmitted through the object to be inspected is detected by a one-dimensional or two-dimensional radiation detector. Then, a pattern of a perspective two-dimensional image of the object contained in the package is recognized by performing image processing using pixel information. Thus, the conventional apparatus determines whether or not abnormality, such as a crack, occurs in the object included in the package occurs. Therefore, the conventional apparatus has problems that large-scale image processing should be performed so as to realize a high-speed inline system, and that both the hardware and software of the apparatus are too costly.
The invention is accomplished in view of such circumstances. Accordingly, an object of the invention is to provide a radiation inspection apparatus and a radiation inspection method that does not need large-scale image processing, which is needed by the conventional apparatus, that the hardware and software for image processing are relatively simple, and that it can reliably be determined with a low-cost configuration whether or not a crack or a nick occurs in an object packaged by a non-transmissive material.
To achieve the foregoing object, according to the invention, there is provided a radiation inspection apparatus, which comprises a radiation generator for generating radiation toward an object to be inspected; a radiation detector disposed in such a way to face the radiation generator, for detecting the radiation transmitted through the object to be inspected and outputting a pixel data of each pixel consisting an image of the object to be inspected; and a data processor unit for performing data processing by using the pixel data outputted from the radiation detector. In this apparatus, the data processor unit calculates a difference between that pixel data of each pixel, which is outputted from the radiation detector, and the pixel data of each of surrounding pixels thereof, and obtains a total of a circumference length of the object to be inspected by totalizing the number of pixels, gray level data obtained by difference processing correspondingly to each of which is within a predetermined gray level range, and determines from a total of the circumference length of the object whether or not a crack or a nick occurs in the object.
The invention obtains an image, in which the pixel gray level of a part corresponding to the contour portion of the object differs from those of the remaining parts thereof, by obtaining the difference between the pixel data of each pixel consisting an image of the object and that of each of the surrounding pixels thereof. The invention achieves the desired purpose by totalizing the number of pixels, whose pixel gray levels are within a predetermined gray level range, and by then determining from a total number of such pixels whether or not a crack or a nick occurs in the object on the basis of the fact that the pixel gray level of the part corresponding to the contour portion differs from those of the remaining parts thereof, instead of recognizing a pattern from image information corresponding to the contour portion.
That is, the difference between the pixel data of each pixel consisting a radiation perspective image of an object to be inspected and each of the surrounding pixels thereof is calculated, so that each of parts corresponding to the contour portions of the object to be inspected has a pixel gray level, which differs from the gray level of parts corresponding to the other portions thereof, and which usually has a deeper (or darker) value than the value of the gray level of parts corresponding to the other portions. Thus, a gray level range, which would include the gray levels of pixels of the part corresponding to the contour portion, is preliminarily set. After the calculation of the difference, a total number of pixels, whose gray levels are within the predetermined gray level range, is calculated. Thus, a total of circumference length of the object to be inspected is obtained. In the case that a crack or a nick occurs in the object, the total of circumference length of the object is longer than that in the case that neither cracks nor nicks occur in the object. Consequently, it can be determined more reliably and easily whether or not cracks and nicks occur therein. Further, software for performing such data processing is simple, as compared with software for pattern recognition by performing image processing on a radiation perspective image. Thus, such data processing can be performed at a high speed by using relatively-low-capacity low-speed hardware.